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Biomedical subjects

A Hiltner

Publications and source records attributed to A Hiltner.

43 records · Page 3Linked to original sources
PubMed1981

Biodegradation of a poly-(alpha-amino acid) hydrogel. II. In vitro.

Proteolytic enzymes have been employed in an in vitro model to simulate the in vivo degradation of a synthetic poly(amino acid) hydrogel. Trypsin and collagenase had no effect on crosslinked poly(2-hydroxyethyl-L-glutamine) but pronase and papain dissolved the hydrogel. The initial effect of papain was to decrease the effective crosslink density without producing soluble material. This effect was similar to that observed previously in vivo. Analysis of the papain digestion products showed that oligomers of degree of polymerization 4-9 were the chief products. The rate at which oligomers were formed increased with increasing crosslink density. This phenomenon was attributed to hydrophobic effects.

Biocompatible Materials↗
PubMed1981

Polarizing light microscopy of intestine and its relationship to mechanical behaviour.

The polarizing optical microscope has been used to observe morphologically the effect of stress on rat and bovine intestine. Collagen fibres about 6 micrometers in diameter were found to be biaxially oriented at approximately +30 degrees and -30 degrees to the longitudinal direction. The fibres are arranged in layers with the fibres in each layer densely packed in parallel undulating arrays. The undulations give rise to the extinction pattern observed in the polarizing optical microscope. The initial response to stress is straightening of the fibres. Gradual straightening of the fibres is related to the increasing stiffness of the tissue observed in the stress--strain relationship. Once the fibres ares straightened, the biaxial orientation of the fibres produces higher strength in the longitudinal direction than in the transverse direction. This organization of intestinal collagen fibres has not been reported previously and is not observed in other biaxial tissues such as skin and aorta. Thus, intestine is a unique tissue for studying the relationship of mechanical behaviour to structure and organization of collagen.

Animals↗
PubMedDate not supplied

The biocompatibility of solution cast and acetone-extracted cast Biomer.

The cellular response to films of cast Biomer and acetone-extracted Biomer were investigated over a 21-day implantation period, using an in vivo cage implant system. Film samples were characterized by scanning electron microscopy (SEM), attenuated total reflectance infrared (ATR-IR), electron spectroscopy for chemical analysis (ESCA) and by contact angle measurements before implantation, and by SEM and ESCA after implantation and cleaning. Cellular and protein components of the inflammatory response were analyzed at periodic observation points after implantation. In addition, film samples were retrieved at 4, 7, and 21 days after implantation and analyzed for leukocyte adhesion by light microscopy and SEM. The results demonstrated that cast Biomer contains an extractable fraction, which when removed significantly improves the biocompatibility of the material.

Animals↗